So I left work this afternoon and the car ran pefectly. I stopped at a convienience store by the house and when I returned and started the car, it was running pretty rough at idle. I thought that was wierd and would clear out so I started to drive home and it just got worse. It was running really rough, was barely making power and was backfiring and sputtering. I limped it like a half mile home and got out and looked and it was even smoking out of the tailpipes. So much so they are now visibly very dirty. I looked under the hood and didn't see anything wrong and no warning lights or anything ever came on. I shut it off and let it sit for a minute and restarted and it seems to be running fine again. Any thoughts on what that might have been about?